Cantilever system for holding and positioning components

ABSTRACT

The present invention relates to a device for lash free positioning of especially components used in optical and optoelectronical equipments relatively to a fixed reference unit using at least two interconnected elastic blocks each consisting of two base elements placed at a distance from each other and interconnected by elastic elements, constituting a cantilevered system as related to one of the base elements. To the system a holder is attached, on which the components to be positioned are fixed, that each elastic block is essentially rigid along a main axis (z) of the elastically undeformed cantilevered system, and is elastic in directions perpendicular to the axis, that the device has mechanisms for adjustment which apply adjustable forces between the basic element, or between some other to the latter fixedly joined element, and the cantilevered system or an arm fixed to this system, which latter may be the holder, acting in chosen directions, which translate or turn the component holder, when the elastic elements are elastically deformed.

The present invention relates to a device for lash free positioning ofespecially components used in optical and optoelectronical equipmentsrelatively to a fixed reference unit using at least two interconnectedelastic blocks, each consisting of two base elements placed at adistance from each other and interconnected by elastic elementsconstituting a cantilevered system as related to one of the baseelements.

BACKGROUND OF THE INVENTION

A modern development of optics is optronics (also termedoptoelectronics). Areas of applications of optronics are e.g. opticalfiber communications, gauges for measurements of dimensions and forindications of positions, sensors for special analysis and for analysisof scattering etc. The optical equipment is comprised by optical,mechanical and electronic building elements.

It is desirable in optronic equipment to integrate the building elementsinto a stable and miniaturized unit. Especially in a development phaseit is also preferred to have some of the elements easily replaceable. Arequirement set for many of the elements is also that they should beadjustable as regards position and attitude, so that the optical beampath strived for in the equipment can be attained. The beam crosssection, in e.g. semiconductor lasers and single mode fibres that areused in optical communications, have a diameter of the order ofmagnitude of micrometers. It is therefore in aligning such equipmentnecessary to be able to make adjustments with an accuracy and precisioncorresponding to a micrometer or submicrometer change in position. It isalso important that components, which have been positioned, keep theirposition and attitude for a very long period of time, also in amechanically adverse surrounding environment. It is common in adevelopment phase that the optronical components are mounted onmechanical units obtained from a standardized building set of opticalbenches, sleds, holders, translational and rotational devices etc. It isunavoidable that such construction becomes bulky unstable and sensitiveto vibrations. This is true even if the individual elements themselvesare capable of e.g. a translation with a sufficient precision. Severaldesigns of spring blocks of the type referred to are known, e.g. throughan article in Journal of Scientific Instruments, Vol. 33, January 1956titled "Some parasitic deflexions in parallell spring movements". Thistype of device has, however, only found a limited use.

The U.S. Pat. No. 4,930,858 refers to a positioning apparatus foroptical fibres, which is intended to make two fibre ends, or one fibreend and a laser beam, parallel in relation to each other. The apparatusconsists of 3 circular plates, provided at a distance from each otherand connected to each other by "shoulders" integrated in the plates,that is by segment formed portions of material. In the plates centralapertures are provided for mounting of e.g. a fibre end in the movableupper plate and to permit free optical beam path to e.g. a laser, whichis mounted in the fixed part of the apparatus.

By means of screws, which apply forces on the plates crosswise these,that is in the axis direction of the apparatus, the upper movable platecan be forced to form a first angle with the central plate, and this, inthe same way with further screws, which act in the axis direction, canbe forced to form a second angle with the bottom plate. In these turningmovements, which occur about the chords of the segments, both themovable plates will be tilted and therewith the part--e.g. the fibreend--which is to be adjusted.

This apparatus known can be used when two directions shall be brought tocorrespond and where it is of no importance if the movable component,which is to be adjusted, in addition to the desired turning alsoperforms an inevitable, that is coupled, translation in the axisdirection. This apparatus known thus cannot be used for positioning ofan optical component, where it is required that the movable componentduring the adjustment maintains its angular position relatively to thefixed component. In other words, one should be able to be translate themovable component to a desired position without it being turned. Furtherit shall be possible in certain applications that the movable componentbe given a desired turn, which is accomplished by giving thepoint/points of action for the forces generated by the adjustmentmechanism a certain location along the main axis of the system, that isthe Z-axis.

The object of the invention and its most important characteristics.

The object of the invention is to produce a positioning device thatallows for translations in serveral directions, a combination oftranslation and rotation or solely a rotation. Further all adjustmentsshall be made free of lash and the dimensions of the components,that areused, shall be sufficiently small, to allow for a compact integrationwith electronic or optoelectronic instruments. These objects have beensolved thereby, that a holder that is attached to the system, on whichthe components to be positioned are fixed, that each elastic block isessentially rigid along a main axis (z) of the elastically undeformedcantilevered system, and is elastic in directions perpendicular to theaxis, that the device has mechanisms for adjustment which applyadjustable forces between the basic element, or between some other tothe latter fixedly joined element, and the cantilevered system or an armfixed to this system, which latter may be the holder, acting in chosendirections, which translate or turn the component holder, when theelastic elements are elastically deformed.

DESCRIPTION OF DRAWINGS

The invention will be further described below with reference to theattached drawings, which show some examples of embodiments.

FIG. 1. shows an end view of the positioning device according to theinvention.

FIG. 2. shows a section along the line II--II of FIG. 1.

FIG. 3. shows on a larger scale a differential screw which in accordancewith FIGS. 1 and 2 is part of the positioning device.

FIG. 4. shows a modified example of an embodiment of the adjustmentdevice according to the invention, partly in sections, and comprising onthe one hand a differential screw and on the other hand a piezoelectricadjustment arrangement.

FIG. 5. shows on a larger scale the holder for components according toFIG. 2 together with components placed inside it, which componentstogether with components in a fixed unit define an optical ray path.

FIG. 6. shows an analogous view to that of FIG. 1 of an extendedpositioning device in which an inner unit, that consists of thepositioning device of FIG. 1, can be translated and/or turned around anaxis perpendicular to the translation.

FIG. 7. shows a section along the line VII--VII of FIG. 6.

DESCRIPTION OF EXAMPLES OF EMBODIMENTS

The positioning device according to the invention shown in FIGS. 1 and2, which is indicated by the number 10 in the drawings, consists of twoelastic blocks 11 and 12, which are joined to each other and with theone system 11 consisting of two base elements 13 and 14 in the shape ofplates which have central apertures. By positioning, in this context, isunderstood both moving and/or turning. The plates mentioned are kept ata distance from each other and joined by a number of, e.g. four, elasticelements 17, which in the embodiment shown consist of rods made ofberyllium copper, stainless steel or the like. One of them, the firstbase element 13, is fixedly united with a housing 18, which has theshape of a rectangular frame, which surrounds both of the spring blocks,while the other one, the base element 14, is movable.

One base element of the second elastic block 12 coincides with themovable base element 14 of the system 11 mentioned above, to which inaddition to the elastic elements 17 there is another set of elasticelements 19 attached, e.g. 4, with a corresponding function as theelastic elements 17. The elastic elements 19 are at its opposite endsattached to a third movable base element 20, which likewise consists ofa plate with a central aperture 21. Its size is chosen such that, with acertain play, it can be contained in the aperture 15 of the first fixedbase element 13. There is an arm 22 screwed into inner threads of theaperture 21, which arm in the embodiment shown consists of a tube, thatserves as a holder for a number of components 23--see FIG. 5--, whichlatter in a certain application can consist of e.g. a collimating lens,a number of optical isolators and filters 25, a focussing lens 26 and aferrule 27, i.e. a ring fixture for a glass fibre guide 28. Further inFIG. 5 number 29 denotes a light source, e.g. a semiconductor laser,that belongs to the fixed reference unit, relatively to which theoptical components 23 shall be positioned with the help of theadjustment mechanisms 30.

The two elastic blocks 11 and 12 constitute together a cantileveredsystem, which through the base element 13 has its root anchored to thehousing. The elastic undeformed cantilevered system has its main axisperpendicular to the plate elements 13, 14 and 20. The positioningdevice of FIGS. 1 and 2 is shown on a larger scale than the natural. Inreality its size is only one or a few centimeters. The parts of theelastic blocks are shaped in such a way that they allow for a compactintegration into relevant portions of the optical and electroopticalequipment. The travel of the adjustment mechanism 30 shall be limited tothe length actually needed and in adjusting, e.g. a fibre guide 28relatively to a laser 29 in a communication system, perhaps only atravel of a few tenths of a millimeter is required.

It shall be possible to integrate multiple functions in the samepositioning device, e.g. it shall be possible to have translations inseveral directions or combinations of translation and turning or solelya turning. To achieve these functions an adjustment mechanism 30 isused, that can affect the elastic blocks 11 and 12 in different ways,depending on how one chooses to let the adjustment screw 31 act indifferent points on the arm 22. In the normal case the points in whichthe forces are chosen to act are fixed points, that with respect to theapplication are situated at given distances from the root of the system.By lengthening the arm 22 in such a way that it extends beyond thecommon base element 14 and by letting the adjustment screw 31 act in apoint at this extended end part, a turning of the the systems in theregion of the third base element 20 is achieved. The strength of theforce applied determines the size of the change in geometry of thecantilevered system. In the example of an embodiment shown in FIGS. 1and 2 two mutually independent alterations can be performed, e.g. twoorthogonal translations. It is for instance also possible to translatethe component holder 22 in one direction and independently turn it aboutan axis, that has the same direction as the translation.

Since the movements of the two elastic blocks are very small, it is alsoimportant that the adjustment mechanism is adapted to these smallmovements. To this end the adjustment screw 31 is suitably made as adifferential adjustment screw, which implies that it consists of a nutpiece 32, that in its outer threads 33 is screwed into the housing 18and which has inner threads, which act together with the outer threads36 of a screw nut piece 35, which has inner threads 37 that in turn acttogether with the outer threads 38 of a screw tap 47, that has an endpart 39 with a noncircular cross section,that corresponds to theaperture 40 of the nut piece 32, through which the end part 39 of thescrew tap extends. The pitch of the threads 34 and 36, that may forinstance be 0.25 mm/turn, deviates somewhat from the pitch of thethreads 37 and 38, which may for instance have a pitch of 0.2 mm/turn,in order to get the translation of the tap scew 47 geared to 0.05mm/turn.

In order to make the adjustment mechanism 30 still more sensitive themodified adjustment mechanism in FIG. 4 can be used, in which case thenut piece 32 of the differential set screw 31 has been split into twoparts, a base fixture 42 and a nut piece 43, inbetween which a tubeshaped piezo electric element 44 has been fixedly arranged, that, whenan electric voltage is applied, gets the length altered and therebytransfers the nut piece 43 axially a distance, that is determined by thevoltage applied.

The adjustment mechanism 30, that applies a force onto the arm 22, doesnot necessarily contain a screw device. The latter can be substituted bysome other force delivering mechanical arrangement or e.g., solely by anelectro- or magnetostrictive element.

In certain cases it may be necessary to perform a positioning in threecoordinates x, y, and z. The modification of the positioning deviceFIGS. 1 and 2 presented in FIGS. 6 and 7 is supplemented by a 4th baseelement 45 arranged outside the elastic elements 11 and 12 in the fixedreference unit, that may be the outer housing of the extendedpositioning device, from which a number of elastic elements 46, which attheir opposite end are attached to the inner housing of the device. Theelastic elements 46 can favourably be flat elastic elements, that onlyallow for movements in the direction of the main axis z of the device.

The invention shown and described is not limited to the embodimentsdemonstrated, but can be varied in numerous different ways within theframe of the patent claims. Positioning devices can be utilized in manyconnections where the emphasis is on precision of movements andalteration of attitudes, that have to be made by small rigidly mountedbuilding elements, e.g. adjustments of lenses and other optical elementsin aligning equipments, movements of objectives in microscopes,balancing of elements in mechanical apparatuses, trimming of the platedistance in electrical capacitors etc.

TABLE OF REFERENCE DESIGNATIONS

10=positioning device

11=1st elastic block

12=second elastic block

13=1st base element, e.g. a plate

14=2nd base element, e.g. a plate

15=central aperture in 1st base element

16=central aperture in 2nd base element

17=elastic elements, e.g. rods

18=housing

19=elastic elements, e.g. rods

20=3rd base element, e.g. a plate

21=central aperture in 3rd base element

22=arm=tube=holder

23=components used in optical and optoelectronic equipment

24=collimating lens

25=optical isolator and filter

26=focussing lens

27=ferrule (ring fixture)

28=glass fibre guide

29=light source, e.g. semiconductor laser, included in the fixedreference unit

30=adjustment mechanism

31=adjustment screw, e.g. differential adjustment screw

32=nut piece

33=outer threads of 32

34=inner threads of 32

35=screw nut piece

36=outer threads of 35

37=inner threads of 35

38=outer threads of 47

39=end part

40=aperture

42=base fixture

43=nut piece

44=piezoelectric element

45=4th base element, e.g. outer housing of the extended positioningdevice, included in the fixed reference unit

46=elastic elements

47=tap screw

z=main axis

I claim:
 1. A device for lash free positioning of components used inoptical and opto-electronical equipment relative to a fixed referenceunit, the device comprising:a fixed first elastic block comprising afirst base element and a second base element, the first base elementbeing adapted to be secured to the fixed reference unit; a movablesecond elastic block comprising a third base element and the second baseelement, the second and third base elements being adapted to be movablerelative to the first base element; the first and second base elementsbeing interconnected by elastic elements and the second and third baseelements being interconnected by elastic elements such that the secondbase element and elastic elements form a cantilevered system withrespect to the fixed first base element, each elastic block beingsubstantially rigid in a z-direction of the cantilevered system andelastic in a x-direction and a y-direction thereof, the x and ydirections being perpendicular to the z-direction; a component holder towhich the optical and opto-electronical equipment components are adaptedto be fixed, the component holder being engaged by the third baseelement; and adjustment means operatively arranged between the fixedreference unit and the component holder for applying forces to thecomponent holder to selectively move the holder in the x and ydirections, the elastic elements of the cantilevered system beingdeformed when the adjustment means applies the forces to displace thecomponent holder.
 2. A device according to claim 1, wherein the fixedfirst base element and the movable third base element are located in afirst plane and the second base element is located in a second planedisplaced from the first plane.
 3. A device according to claim 1,wherein the first base element defines a first aperture, the second baseelement defines a second aperture, and the third base element defines athird aperture to provide a central optical path through thecantilevered system in the z-direction.
 4. A device according to claim1, wherein the component holder is a cantilevered arm that can bedisplaced in the x and y directions by the adjustment means.
 5. A deviceaccording to claim 1, wherein the adjustment means includes one or moreset screws.
 6. A device according to claim 1, wherein the adjustmentmeans includes one or more electro or magnetostrictive elements.
 7. Adevice according to claim 5, wherein the cantilevered system issupported within a first housing to which the first base element isrigidly attached, the second base element being a common element formingpart of each elastic block, the third base element being disposed in aplane common to that of the first base element, the set screws beingadjustably mounted in the first housing and operatively arrangedrelative to the component holder to apply forces thereto in mutuallyperpendicular x and y directions.
 8. A device according to claim 5,wherein each set screw is a differential screw including first, secondand third parts screwed into each other, the first part and second partbeing threadably connected by a first thread pitch, the second and thirdparts being threadably connected by a second thread pitch different fromthe first thread pitch, thereby defining a gear ratio between the first,second and third parts.
 9. A device according to claim 7, wherein thefirst housing is placed in a second housing, the second housing beingtranslatable and rotatable relative to the fixed reference unit.
 10. Adevice according to claim 1 wherein the elastic elements includerod-shaped springs.
 11. A device according to claim 1 wherein theelastic elements include plate-shaped springs.
 12. A device according toclaim 8 comprising a piezoelectric device operatively connected to thedifferential screw so as to enable adjustment of the position of saidscrew.
 13. A device for lash free positioning of components used inoptical and opto-electronical equipment, the device comprising:a rigidtubular frame having a longitudinal axis and having opposite upper andlower ends and a first aperture of a first predetermined size definedthrough the tubular frame; a flat flange having an upper side and alower side, the flange being secured to the lower end of the frame andextending inwardly into the central opening to define a second aperturehaving a second predetermined size that is smaller than the firstpredetermined size; an upper plate having a top surface and a bottomsurface, the upper plate being disposed within the central opening ofthe frame adjacent the upper end of the frame so that the upper plate isdisplaced from the flange, the upper plate defining a third aperturebeing substantially concentric with the second aperture of the flangeand having a third predetermined size that is smaller than the secondpredetermined size of the second aperture; a first rod having oppositeends, one end being operatively attached to the upper side of the flangeand the other end being operatively attached to the bottom surface ofthe upper plate so that the rod extends within the central opening andis substantially parallel to the longitudinal axis of the frame, thefirst rod being substantially rigid in a longitudinal z-direction butflexible in a lateral x-direction and a lateral y-direction, thez-direction being parallel to the longitudinal axis of the firstaperture and perpendicular to the x and y-directions, a lower platehaving a top surface and a bottom surface, the lower plate beingdisposed within the second aperture defined by the flange and displacedfrom the upper plate, the lower plate defining a fourth aperture havinga fourth predetermined size that is smaller than the third predeterminedsize of the third aperture and substantially concentric therewith; asecond rod having opposite ends, one end being operatively attached tothe bottom surface of the upper plate adjacent the third aperture, theother end being operatively attached to the top surface of the lowerplate so that the second rod is substantially parallel to the first rod;the second rod being substantially rigid in the longitudinal z-directionbut flexible in the lateral x and y-directions so that the upper andlower plates are movable relative to the frame in the x andy-directions; a tubular component holder to which the optical andopto-electronical equipment components are adapted to be held, thecomponent holder having opposite ends and a substantially constantdiameter, one end being disposed within the fourth aperture and fixedlyattached to the lower plate and the other end being disposed within thethird aperture so that the tubular component is substantially parallelto the first and second rods; a first set screw adjustably mountedwithin a first threaded lateral hole defined by the frame, the first setscrew being parallel to the x-direction and being adapted to be extendedlaterally and inwardly in the x-direction by rotating the first setscrew within the first threaded hole to engage the component holder tomove the component holder in the x-direction, the first and second rodsbeing adapted to deform in the x-direction when the first set screwmoves the component holder in the x-direction; and a second set screwadjustably mounted within a second threaded lateral hole defined by theframe, the second set screw being parallel to the y-direction andperpendicular to the first set screw, the second set screw being adaptedto be extended laterally and inwardly in the y-direction by rotating theset screw within the second threaded hole to engage the component holderto move the component holder in the y-direction, the first and secondrods being adapted to deform in the y-direction when the second setscrew moves the component holder in the y-direction, whereby theposition of the component holder relative to the frame may be adjustedin both the x and the y directions by the set screws.